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What are others seeing for co2 levels while sleeping?

tech1234 | Posted in General Questions on

I am curious what others with PGH houses are seeing for co2 levels while sleeping. I recently got a Aranet4  (calibrated it) and just began getting some data for a few days. I am peaking at just over 1000 ppm early in the morning just before getting up. My house seems to generally be at low 700’s most of the day. I am generally sleeping well but now that I see the data I wonder if I could be waking more well rested. I’ll list some details below:

Less than 1 year old PGH build – 1900 sqft
0.6 ach50
Broan AI ERV (current settings: 50 cfm Continuous –  119cfm Boost)
Lots of boost events happen in a day, I’d guess 4+ hours a day are boost levels
I use “boost” for light cooking and bathroom use (range hood with MUA for serious cooking)
2 adults and a large dog (dog sleeps in bedroom too)
NO combustion appliances

This is my 3rd high performance house (I am a builder) and have always been on team “don’t over ventilate”  although as more IAQ data comes out I am leaning towards turning things up a bit but I also don’t want too much of an energy penalty.

(one option for my ERV is to schedule a “Boost” event once late in the night)

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  1. matthew25 | | #1

    Do you sleep with your bedroom door shut? Perhaps the overall level of the house is fine you just have a high concentration in the bedroom.

    1. tech1234 | | #3

      I should have added- bedroom door open. Also the door has a large undercut if it ever were to be closed.

  2. Deleted | | #2


  3. pnw_guy | | #4

    Boosting the ERV at night may be more efficient, but another option--if you have a ducted HVAC system w/ an efficient ECM blower on the indoor unit--would be to have the air handler blower run 15-30 minutes per hour to circulate air. Although since you said you keep the bedroom door open, that may not make much of a difference.

    1. andyfrog | | #5

      Does the ERV have a recirculation mode already?

      1. tech1234 | | #9

        Andy- yes the ERV does have a recirculation mode, scheduling a night time recirculation event is and interesting idea. I'll have to try that and see what my co2 readings do.

    2. tech1234 | | #7

      only ducts in the house are the ERV. (1 ductless mini split per floor)

  4. aaron_p | | #6

    We are seeing 1300-1700ppm peaks at night in a newer construction home with some limited air sealing so far. Looking to add ERV to our house to help as I continue to air seal.

    From sources and studies around the internet it seems that staying below 1000ppm for sleep is desired. Might not take much for you to get there maybe bump the continuous up a little?

    How do you like the Broan unit?

    1. tech1234 | | #11

      aaron- I really like the controls (I have a master wall display panel in the kitchen (very nice) and countdown timer boost buttons in each bath) and the self balancing tech. I am slightly disappointed with the build quality inside the unit (filter sealing is awful, I'll likely mod this) and the core rating could be better. overall for the price its decent.

  5. user-5946022 | | #8

    Data source: PGH, ACH 1.1/50pa, ducted minis with fan running 24/7 (so circulating air), 3 supply air diffusers in bedroom suite area, dedicated transfer duct from bedroom to within 8' of return air (outside of bedroom area), door pulled closed to just before latch hitting strike (so person going to bed later can enter without waking sleeping occupant, and vice versa in am), Airthings WavePlus in bedroom, 2 adults, no pets, a few plants (if that matters), major metro area, but the portion of the city with single family homes and duplexes, about 1/2 block from 100's of apartments. Make up air, unconditioned but filtered, dumps into master bedroom when kitchen hood is turned on, which is every few days.

    When the house is unoccupied (ie out of town), the CO2 level drops to between 406 and 420 and stays.

    When the house is occupied (WFHx2) and closed up, the CO2 level gets down to the 580's during the day, and 840's-860's at night

    When the house is occupied (WFHx2) and windows are opened for a bit during the day (never at night) the CO2 level can get down to the 480's in the day, and peak in the 650's-750's at night.

    So a 200-300 rise in CO2 at night.

    No idea how accurate the meter is.

    HOWEVER, when I first moved in and started measuring I was shocked that it regularly went over 1000 at night. I had changed all the filters the night before moving in. When I changed the filters again 2 months later, the CO2 IMMEDIATELY dropped and has stayed down since. I believe the filters caught so much latent dust in the air from construction and moving that they were clogged and not moving the air well enough.

    1. tech1234 | | #10

      Interesting data points to compare. Thanks for sharing

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